The Mishnah discusses the minimum quantity of food, known as a shiur, one must consume on Yom Kippur to incur liability. This shiur is defined as a large date, or kotsevet gasah, including its pit. The Gemara delves into the precise meaning of "including its pit."
Rav Pappa poses a question: Does the mentioned date refer to its volume with the pit inside, or without it? Rashi clarifies Rav Pappa's query: Is the shiur the combined volume of the date and its pit, or is it either the volume of the date or the volume of the pit, implying they are equivalent? Tosafot, however, challenges Rashi's interpretation, pointing out that the Mishnah explicitly states "and its pit," not "or its pit." To reconcile Rashi, later commentators explain that the question is about how the measurement is taken: Is it the volume of the date with the pit still embedded, or the separate volumes of the date and the pit added together? The distinction arises because a date with its pit inside might occupy a slightly larger volume due to air pockets, whereas a separated date and pit would be measured without such expansion.
Rav Ashi raises a similar question concerning a different law: the shiur for a bone fragment (etsem) to transmit ritual impurity (tumah). This shiur is the size of a barley grain (seorah). Rav Ashi asks if this refers to a barley grain with its husk (klipah) or without it, and whether it refers to a moist (lachah) or dry (yevashah) grain. If it includes the husk or is moist, its volume would be larger.
The Gemara notes that Rav Ashi did not have Rav Pappa's question regarding Yom Kippur, because the Mishnah specifies a "fat date" (kotsevet gasah), implying the largest possible size, which would naturally include the pit in its most expansive state. Conversely, Rav Pappa did not have Rav Ashi's question regarding the barley grain because a moist barley is called a shibolet, and a barley without its husk is called an oshla. Thus, the term seorah itself implies a dry barley with its husk, resolving the ambiguity for Rav Pappa.
Rabba, in the name of Rav Yehuda, states that the shiur of a kotsevet gasah is "more than an egg" (yeteirah mik'beitza). The Sages (Rabbanan) had a tradition that a person's mind is at ease (mitva da'ateh) when consuming this amount. This "ease of mind" is crucial for Yom Kippur, where the obligation is to afflict oneself (inuy). While most forbidden eating (achilat issur) has a shiur of an olive's volume (k'zayit), the Torah's command for Yom Kippur is "you shall afflict yourselves" (ve'anitem). Eating a k'zayit might be considered eating, but it does not necessarily bring a sense of satisfaction that removes the affliction. Therefore, the shiur for liability on Yom Kippur is the larger amount that brings ease of mind, which is more than a k'beitza. Less than this amount, one's mind is not at ease, and the affliction continues.
The Gemara challenges this with a story from Masechet Sukkah. Rabban Yochanan ben Zakkai was brought a cooked dish to taste in the Sukkah. To Rabban Gamliel, they brought two dates (shtei kotvot) and a jug of water. The Sages instructed to bring these items into the Sukkah, not because the law (halacha) required it, but because they wished to be stringent (machmir). This implies that two dates are less than a k'beitza, and thus would not obligate one to eat in the Sukkah. The story continues with Rabbi Tzadok, who ate food less than a k'beitza outside the Sukkah, without ritual hand-washing (netilat yadayim), and without reciting the Grace After Meals (Birkat Hamazon). This further suggests that a k'beitza is the threshold for eating in the Sukkah and for reciting Birkat Hamazon. If two dates are less than a k'beitza, how can a single kotsevet gasah with its pit be more than a k'beitza, especially if the date itself is assumed to be larger than its pit?
Rav Yirmiyah responds that, indeed, two dates without their pits are less than a k'beitza, but a kotsevet gasah with its pit is more than a k'beitza. This implies that the pit itself is larger than the date's flesh. Rav Pappa supports this by citing a popular saying: "Two kav of dates contain more than one kav of pits," indicating that the volume of the pits exceeds that of the date flesh. Therefore, a date with its pit would be larger than two dates without pits, thus exceeding a k'beitza.
Rava offers an alternative explanation for the Sukkah narrative: The reason the Sages were stringent was not due to the quantity, but because dates are fruits (peirot), and fruits do not obligate one to eat in the Sukkah. Therefore, even if two dates were more than a k'beitza, they would still not require eating in the Sukkah. The Sages' stringency was to treat them as if they were bread, which does obligate eating in the Sukkah.
The Gemara challenges Rava's view with a statement from Rebbe: When learning with Rabbi Elazar ben Shamu'a, they were brought figs and grapes, which they ate as a casual snack (achilat arai) outside the Sukkah. This implies that if they had eaten them as a substantial meal (achilat keva), they would have been obligated to eat them in the Sukkah, contradicting Rava's assertion that fruits never require a Sukkah. The Gemara offers two resolutions: Either they ate a large quantity of fruit but treated it as a snack, or they ate a substantial fruit meal along with a small, snack-like quantity of bread, and the "snack" status applied only to the bread, allowing them to eat outside the Sukkah. In both interpretations, the underlying principle remains that fruit itself does not obligate one to eat in the Sukkah, regardless of quantity.
A further proof is brought from Rabbi Eliezer's opinion in Masechet Sukkah, which states that one must eat fourteen meals in the Sukkah. He says that one can fulfill this obligation by eating "types of targima" (minei targima), which Rashi explains as non-bread items like dips or condiments, or meat and fish. The Gemara asks: If fruits obligated one to eat in the Sukkah, why didn't Rabbi Eliezer mention fruits as a way to fulfill the obligation? This suggests that fruits do not require a Sukkah. The Gemara initially answers that minei targima actually refers to fruits. An alternate answer is that Rabbi Eliezer's statement refers to a place where fruits were not readily available, so he gave an example of other items that could fulfill the obligation.
Rav Zevid introduces a different opinion: The shiur of a kotsevet gasah is "less than an egg" (chasera mik'beitza). This is supported by a Mishnah in Masechet Beitzah regarding the prohibition of leavened products (chametz) on Pesach. Beit Shammai states that the shiur for leavening agent (se'or) is a k'zayit, while for chametz it is a kotsevet. The Gemara explains that the Torah differentiates between se'or and chametz, implying different shiurim. Since se'or is a more potent leavening agent, it has the stricter shiur of a k'zayit. Chametz, being less potent, has a larger shiur. If a kotsevet gasah were more than a k'beitza, Beit Shammai should have simply said a k'beitza for chametz, as it is a more commonly used shiur (e.g., for ritual impurity of food, tum'at ochlin). The fact that Beit Shammai uses kotsevet implies it's an intermediate shiur, larger than a k'zayit but smaller than a k'beitza.
The Gemara counters this: Perhaps there's a distinction between a "large date" (kotsevet gasah) and a "regular date" (kotsevet stam). A kotsevet gasah might be more than a k'beitza, while a kotsevet stam is equivalent to a k'beitza, and Beit Shammai refers to the latter. Or, it could be that the shiurim of a k'beitza and a kotsevet are actually the same, and Beit Shammai simply chose one term over the other.
The Gemara then brings a conclusive proof from the laws of Grace After Meals (Birkat Hamazon). The question is, how much bread must one eat to be obligated in Birkat Hamazon? Rabbi Meir says a k'zayit, based on the verse "you shall eat" (ve'achalta), which refers to eating, and "you shall be satisfied" (vesavata), which he interprets as drinking. Eating, by definition, is a k'zayit. Rabbi Yehuda says a k'beitza, interpreting the verse as "eating that brings satisfaction" (achilah sheyesh bah seviah), which is a k'beitza. If a kotsevet gasah is more than a k'beitza, and a k'beitza brings satisfaction, then it should also bring "ease of mind." If so, on Yom Kippur, one should be liable for eating a k'beitza, not more than a k'beitza. The fact that the shiur for Yom Kippur is more than a k'beitza, based on "ease of mind," while Birkat Hamazon is on a k'beitza for "satiation," indicates that "ease of mind" (mitva da'ateh) is achieved with a smaller quantity than "satiation" (seviah). Therefore, a kotsevet gasah, which brings ease of mind on Yom Kippur, must be less than a k'beitza, which brings satiation for Birkat Hamazon. This establishes that the shiur of a kotsevet gasah is indeed less than a k'beitza.